title: Estrogen influences osmotic secretion of AVP and body water balance in postmenopausal women.
abstract: To determine if estrogen upregulates osmotic secretion of arginine vasopressin (AVP) and alters body water balance, we infused hypertonic (3% NaCl) saline in 6 women (68 +/- 3 yr) after 14 days of 17 beta-estradiol (transdermal patch, approximately 0.1 mg/day, E2) and placebo (control) administration. Hypertonic saline was infused at 0.1 ml.kg-1.min-1 for 120 min, and after a 30-min equilibration period, the subjects drank water ad libitum for 180 min. E2 increased basal plasma estradiol concentration from < or = 12 to 80 +/- 12 pg/ml and plasma AVP concentration (P[AVP]) from 2.1 +/- 0.7 to 3.1 +/- 0.8 pg/ml (P < 0.05), but not plasma osmolality (Posm, 288 +/- 1 and 287 +/- 1, for control and E2, respectively). Hypertonic saline infusion increased Posm by 18 +/- 1 and 17 +/- 1 mosmol/kgH2O and P[AVP] by 5.2 +/- 0.5 and 4.9 +/- 0.4 pg/ml for control and E2 treatments, respectively. The P[AVP]-Posm relationship shifted upward after E2, with no change in sensitivity (slope, 0.36 +/- 0.02 and 0.33 +/- 0.03 pg.ml-1.mosmol-1 for control and E2, respectively). Water intake was similar between control and E2 (24 vs. 22 ml/kg), but by 180 min of drinking, urine output and free water clearance (CH2O) were reduced by 5.6 +/- 2.3 ml/kg and 2.6 +/- 2.0 ml/min, respectively (P < 0.05) after E2. Plasma aldosterone concentration was unaffected by E2, but fractional sodium excretion was reduced from 2.7 +/- 0.5 to 1.7 +/- 0.4% (P < 0.05) at 180 min of drinking. Our data suggest that E2 augments osmotic AVP secretion, thereby implicating elevated AVP as a contributor to water retention in high E2 states; however, an increase in renal sodium reabsorption was a major component of the enhanced fluid retention.
authors.affiliation: John B. Pierce Laboratory, Yale University School of Medicine, New Haven, Connecticut 06519, USA.
authors.forename: N S
authors.initials: NS
authors.lastname: Stachenfeld
authors.forename: L
authors.initials: L
authors.lastname: DiPietro
authors.forename: S F
authors.initials: SF
authors.lastname: Palter
authors.forename: E R
authors.initials: ER
authors.lastname: Nadel
mesh_terms: D000450:Aldosterone / Q000097:blood; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D005260:Female; D005919:Glomerular Filtration Rate; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007262:Infusions, Intravenous; D007263:Infusions, Parenteral; D008875:Middle Aged; D010710:Phosphates / Q000097:blood; D017698:Postmenopause / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000097:blood; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology; D012964:Sodium / Q000097:blood; D014882:Water-Electrolyte Balance / Q000187:drug effects*
chemical_list: D006454:Hemoglobins; D010710:Phosphates; D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin; D000450:Aldosterone; D004958:Estradiol; D012964:Sodium; D011188:Potassium